The Mason-bees 



find their way not by sense of smell, but really 

 land truly by sense of sight; for, every time 

 that I alter the appearance of the track in 

 any way whatever — whether by my destruc- 

 tive broom, my streaming water, my green 

 mint, my paper carpet or my golden sand — 

 the returning column calls a halt, hesitates 

 and attempts to account for the changes that 

 have taken place. Yes, it is sight, but a very 

 dull sight, whose horizon is altered by the 

 shifting of a few bits of gravel. To this short 

 sight, a strip of paper, a bed of mint-leaves, 

 a layer of yellow sand, a stream of water, a 

 furrow made by the broom, or even lesser 

 modifications are enough to transform the 

 landscape; and the regiment, eager to reach 

 home as fast as it can with its loot, halts un- 

 easily on beholding this unfamiliar scenery. 

 If the doubtful zones are at length passed, it 

 is due to the fact that fresh attempts are con- 

 stantly being made to cross the doctored strips 

 and that at last a few Ants recognize well- 

 known spots beyond them. The others, rely- 

 ing on their clearer-sighted sisters, follow. 



Sight would not be enough, if the Amazon 

 had not also at her service a correct memory 

 for places. The memory of an Ant 1 What 

 146 



